Summary

Pax1 is a transcriptional regulatory protein expressed during mouse embryogenesis and has been shown to have an important function in vertebral column development. Expression of Pax1 mRNA in the embryonic thymus has been reported previously. Here we show that Pax1 protein expression in thymic epithelial cells can be detected throughout thymic development and in the adult. Expression starts in the early endodermal epithelium lining the foregut region and includes the epithelium of the third pharyngeal pouch, a structure giving rise to part of the thymus epithelium. In early stages of thymus development a large proportion of thymus cells expresses Pax1. With increasing age, the proportion of Pax1-expressing cells is reduced and in the adult mouse only a small fraction of cortical thymic stromal cells retains strong Pax1 expression. Expression of Pax1 in thymus epithelium is necessary for establishing the thymus microenvironment required for normal T cell maturation. Mutations in the Pax-1 gene in undulated mice affect not only the total size of the thymus but also the maturation of thymocytes. The number of thymocytes is reduced about 2- to 5-fold, affecting mainly the CD4+8+ immature and CD4+ mature thymocyte subsets. The expression levels of major thymocyte surface markers remains unchanged with the exception of Thy-1 which was found to be expressed at 3- to 4-fold higher levels.

Reference

AndersonG.,

JenkinsonE. J.,

MooreN. C.,

OwenJ. J.

(1993) MHC class II-positive epithelium and mesenchyme cells are both required for T-cell development in the thymus.Nature362, 70–73

(1993) Proenzyme form of cathepsin L produced by thymic epithelial cells promotes proliferation of immature thymocytes in the presence of IL-1, IL-7, and anti-CD3 antibody.Cellular Immunology150, 124–136

Similar articles

Other journals from The Company of Biologists

We are aware that the COVID-19 pandemic is having an unprecedented impact on researchers worldwide. The Editors of all The Company of Biologists’ journals have been considering ways in which we can alleviate concerns that members of our community may have around publishing activities during this time. Read about the actions we are taking at this time.

Please don’t hesitate to contact the Editorial Office if you have any questions or concerns.

Paul François is an Associate Professor at McGill University, Canada and has recently joined the Development team as an Associate Editor. We caught up with Paul over Skype from his home in Montreal, Canada, to find out more about his background and research – and what he is excited about in the field of computational and theoretical biology.

Researchers at nine institutions in Ireland can now publish an unlimited number of Open Access articles in Development, immediately and at no cost to them, following a three-year Read & Publish agreement between The Company of Biologists and IReL. Find out more and see the growing list of participating institutions.